Filament wound multi-color arrow shaft

ABSTRACT

In certain preferred embodiments, the present invention provides arrow shafts and a method of making arrow shafts with two or more colors. Preferably the shafts incorporate filament winding to leave two or more visible colors in the finished shaft in a regular or irregular pattern. Preferably the multi-colored pattern extends a substantially distance through the thickness of the shaft.

FIELD OF THE INVENTION

The present invention relates generally to the field of arrow shafts.

BACKGROUND OF THE INVENTION

Archery arrows with graphite or “composite” shafts are gaining in acceptance. Graphite shafts have reduced weight plus generally greater flex and strength than traditional materials. Traditionally however, graphite shafts have suffered from inconsistent manufacturing, higher costs, a soft feel and higher breakage rates. Composite graphite shafts have normally been made by either a sheet-rolling method or a filament winding method.

In the sheet-rolling or sheet-wrapping method, carbon, glass or other fibers are impregnated with a plastic resin and placed in a parallel matrix to form a broad sheet or prepreg. The prepreg is then cut into smaller sheets with all of the fibers at a particular angle to the axis of the intended mandrel, the angle can be between 0° and 90°. These flags are then rolled around a mandrel to form various layers or plies. The layers are then cured to form a composite and the mandrel is removed.

In the filament winding method, fibers are collected into groups called “tows” and each tow is impregnated with resin and wrapped around the mandrel to form the layers prior to curing. Filament winding generally results in an improved shaft with greater consistency in manufacture and control of fiber placement.

Archery is generally used for hunting or target shooting. Various colors and patterns for arrows are sometimes desired. Arrows can be decorated using regular patterns for a desired ornamental look or irregular patterns such as camouflage patterns. Typical methods of imparting color and patterns to graphite arrow shafts include painting the material or wrapping the shaft in a tight-fitting, decorated material, for example a shrink-wrap film or decal. A film or decal may leave visible seams in the pattern. In an alternate method, some manufacturers have embedded a decorated material in a prepreg sheet to be wrapped in the outer layer around a shaft; however, this option is not available in filament winding. In some instances, the shafts are encased in a protective transparent mask or film after the decoration is added. These shafts are vulnerable to the outer decorative patterns being worn away or damaged for example due to heat and friction or scratches after a period of use.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a method is disclosed of making an arrow shaft having multiple graphite plies. The method includes forming an arrow shaft core of one or more filament wound or sheet-rolled fiber reinforced graphite plies around a mandrel. A first filament wound ply including at least a first color is wound around the core. A second filament wound ply including at least a second color differing from the first color is wound around the core and the first ply. The first filament wound ply and the second filament wound ply form an arrow shaft outer layer with a thickness and having an outer diameter equal to or greater than the desired shaft finished outer diameter. The shaft is then finished, including removing the mandrel from the shaft, and defining an arrowhead mounting portion and a nocking point portion on the shaft.

In another embodiment of the present invention, a method is disclosed of making an arrow shaft having multiple graphite plies. The method includes winding filaments including at least a first color around a mandrel, and wrapping filaments of at least a second color differing from the first color around the mandrel. The filaments are incorporated in the thickness of an arrow shaft, and the first color and the second color create a color pattern extending through at least a substantial portion of the thickness of the shaft. The shaft is then removed from the mandrel, and an arrowhead mounting portion and a nock mounting portion are on the defined shaft.

In yet another embodiment of the present invention, a composite arrow shaft is formed from multiple fiber reinforced graphite plies forming a core for an arrow shaft having two ends. The core is formed of one or more filament wound or sheet-rolled fiber reinforced graphite plies; and an outer layer is formed of at least one ply filament wound around the core to form an arrow shaft with a desired total diameter. The outer layer preferably includes filaments of at least two different colors. The shaft includes an arrowhead mounting section at one end of the shaft and a nocking section at the opposing end of the shaft.

In yet another embodiment of the present invention, a composite arrow shaft with a length is formed from multiple fiber reinforced graphite plies. The shaft is formed with one or more filament wound plies, and includes a first filament wound portion including filaments of a first color, and a second filament wound portion including filaments of a second color. Preferably the first color is different from the second color.

It is an object of the invention to provide an improved arrow shaft.

Further objects, features and advantages of the present invention shall become apparent from the detailed drawings and descriptions provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an arrow according to a preferred embodiment of the present invention.

FIGS. 2A and 2B are perspective views of steps in a sheet-rolling process.

FIG. 2C is a cross-sectional view of a shaft made with the sheet-rolling process.

FIGS. 3A, 3B and 3C are perspective views of the process of filament winding used in some embodiments of the present invention.

FIG. 4 is a perspective view of filament winding over sheet-rolling wrapping in one embodiment of the present invention.

FIGS. 5A and 5B are cross-sectional, cut-away views of an arrow shaft according to certain embodiments of the present invention.

FIGS. 6A, 6B and 6C are partial views of wrapping and winding patterns in certain embodiment of the present invention.

FIGS. 7A and 7B are partial views of an alternate preferred embodiments of finished shaft views according to the present invention.

FIGS. 8A and 8B are alternate preferred embodiments of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations, modifications, and further applications of the principles of the invention being contemplated as would normally occur to one skilled in the art to which the invention relates.

In certain preferred embodiments, the present invention provides arrow shafts and a method of making arrow shafts with two or more colors. Preferably the shafts incorporate filament winding using two or more colors to leave two or more visible colors in the finished shaft in a multi-colored regular or irregular pattern. Preferably the multi-colored pattern extends a substantial distance through the thickness of the shaft.

The present invention provides an improved archery arrow shaft formed with an elongated body using a combination of fiber-reinforced graphite composites. A typical arrow 8 made in accordance with the present invention is illustrated in FIG. 1, and includes shaft or body 10, arrowhead section 12, fletchings 14 and a nock or nocking point section 16. Shaft or body 10 is typically a hollow tube, often with threaded inserts or portions at the two ends which are designed to connect to an arrowhead or a nocking piece.

“Graphite” or “composite” herein are intended to have their art recognized meanings, generally including fibers in a resin material. The fibers are typically made of graphite, carbon, glass, boron, synthetic fibers such as Kevlar®, fiberglass or other conventional materials, and are made individually in filament form to create a filament tow, or in a parallel resin matrix to form a sheet or prepreg.

Some graphite arrows are made using a sheet-rolling process, such as is illustrated in FIGS. 2A-2C. For example, in FIG. 2A flag or tapered sheet 22, having fibers at an angle, such as 45°, is rolled around a mandrel 15 to form a first layer or ply. Next, flag 22′, having fibers at the opposite angle to flag 22, is rolled around mandrel 15 and first sheet 22, as shown in FIG. 2B. Additional plies at desired angles can then be rolled to form a sufficient number of layers to reach a desired shaft thickness and weight. Some sheets extend the length of the mandrel and are rolled around the diameter, alternately a sheet can be broadly spirally wound on the mandrel. Short flags are sometimes applied to specific sections for reinforcement and/or to provide an oversized finished section which may be reduced. A cross-section of a six ply shaft is illustrated in FIG. 2C included angled flags 22, 22′, and a short flag 22″. Additional plies are not numbered.

The angle of the fibers in a ply can range from 0° to 90° from the longitudinal axis of the mandrel. Intermediate angles in sheet-rolled plies are generally balanced with a ply having fibers angled in the opposite direction. Flags with longitudinal fibers (0°) generally have more effect on flex and bending strength, while fibers with higher angles generally have more effect on torque. Once a sufficient number of layers are applied, the shaft is cured and sanded for finishing. Shafts made with sheet-rolling alone are often criticized as mechanically inconsistent, for example for including seams where sheets overlap, which can cause inconsistent radial stiffness.

Filament wrapping, as illustrated in FIGS. 3A-3C, is a more exact process than sheet-rolling and typically involves precise equipment and control to create a desired shaft. Instead of using a sheet 22, one or more resin impregnated tows 24 are individually wound back and forth around the mandrel 15 at an angle to form a layer or ply. Typical tows range from 2,000 to 80,000 fibers, such as 3K, 6K, 12K, 48K and 80K tows, with some preferred tows having approximately 12,000 fibers. A tow may be pre-impregnated with resin or bathed with resin during the feeding process. Generally a tow is formed in one color, although optional a tow can include fibers of two or more colors.

The size and spacing of tows in FIGS. 3A-3C is exaggerated for clarity. A feeder 17 and its relative movement to mandrel 15 control the angle and density of the filament winding around the mandrel. Typical winding patterns include substantially circular “hoop” winding at substantially perpendicular angles or spiral or “helical” winding at oblique angles. Feeder 17 typically includes guides for tow 24, generally fed from a spool and resin bath (not shown). As one example, feeder 17 may include rollers 18 to guide tow 24 and optionally to remove excess resin by pinching. The mandrel is typically rotated while the feeder 17 traverses the length of the shaft, although alternately the feeder 17 can orbit a fixed mandrel and/or the mandrel traverses relative to the feeder. The speed and relative movement of mandrel 15 and feeder 17 are often computer controlled to precisely control filament placement.

After a tow is wound one direction on a shaft, traditionally the angle of winding and direction is reversed so that a particular layer or ply may have windings at opposite angles as shown in FIG. 3C. Depending on the winding angle, tow width and underlying surface, a filament layer develops a pattern of peaks and valleys along the length of the shaft. Normally a number of plies form a shaft. Computer controlled filament winding allows precise control of the winding process, enabling the machine to change the winding angle between plies or during a ply, to adjust ply thickness and/or to select the placement of individual fibers. Filament winding also allows the introduction of different weave patterns, helping to control weight and flex. Filament winding generally results in a higher degree of mechanical consistency than sheet-rolling.

One example of a hybrid composite, illustrated in FIG. 4, has a core of one or more plies formed on mandrel 15 by sheet-rolling with flags, such as flag 22, and an outer layer of one or more filament wound plies placed over the core using tows such as tow 24. A hybrid composite having a core of sheet-wrapped layers and an outer layer of filament wound layers provides more combinations of attributes than sheet-rolling or filament winding alone.

As illustrated in cross-section in FIGS. 5A and 5B, certain preferred embodiments of the invention include a shaft 10 (shown on a mandrel 15). Shaft 10 can be of a uniform construction or with a core portion 20 covered by an outer layer portion 25. The shaft defines a thickness between the inner diameter ID and the outer diameter OD. In one example, the shaft has a desired inner diameter ID of approximately 0.244 inches and a desired outer diameter OD of approximately 0.290 inches. In one embodiment, a shaft or composite body 10 is made from a number of layers sheet-rolled or filament wound or a combination thereof to form core 20, and a number of plies filament wound over core 20 to form outer layer 25. Typically there are about 4-10 plies in a shaft 10.

In certain preferred embodiments, the shaft includes filament wound plies in outer layer 25 having two or more colors. By way of further illustration, FIGS. 6A-6C show diagrammatic views of the plies used in embodiments 10, 10′ and 10″ of the present invention. Sizes, spacing and positioning of the plies are exaggerated for illustration. FIG. 6A illustrates a shaft 10 on a mandrel 15, having a core 120. Core 120 may be sheet rolled or filament wound. At least one ply 124 of a tow with a first color is filament wound around core 120. At least one ply 126 of a tow with a second color, different from the first color, is filament wound around core 120, and optionally with or around ply 124, to create an interference pattern between ply 124 and ply 126. Additional plies of the same or different colors can be added as desired to form a desired thickness with a diameter equal to or slightly greater than a desired ultimate shaft outer diameter.

FIG. 6B illustrates a portion of an alternate shaft 10′, with a core 120′ filament wound around mandrel 15. Core 120′ includes at least one ply 124 of a tow with a first color. An outer layer including at least one ply 126 of a tow with a second color is filament wound around core 120′ to create an interference pattern between ply 124 and ply 126. Additional plies of the same or different colors can be added as desired.

A further embodiment of a shaft 10″ is illustrated with a portion in FIG. 6C. Shaft 10″ includes first filament wound ply 124 of a first color, second filament wound ply 126 of a second color and third filament wound ply 128 of a third color. Plies 124, 126 and 128 may form the entire thickness of shaft 10″ or alternately may be wound as an outer layer around a sheet wrapped or filament wound core.

In certain preferred embodiments, the two or more colors visible on the outer surface of the shaft extend a substantial distance through the thickness of the shaft between the outer diameter OD and inner diameter ID. For example, the color pattern may extend through the thickness of outer layer 25, and may optionally extend through the entire thickness of shaft 10, being incorporated into the outer layer 25 and the core 20, if a core is present.

As each ply is filament wound onto the shaft, it creates a pattern of peaks and valleys. A combination of multiple filament wound plies creates an interference pattern of overlapping peaks and valleys. The interference pattern may result in an uneven outer diameter surface which may partially show each color which has been wound. To remove and minimize the uneven outer diameter, the shaft is sometimes built to a larger outer or “sacrifice” diameter than is ultimately desired, and is later finished, for example, by curing, grinding and/or sanding to the desired outer diameter and weight. As one example, the sacrifice layer may be approximately 10% larger than the desired final shaft outer diameter. One method of grinding or finishing uses a centerless grinder moving in a direction opposite the shaft rotation and which traverses the length of the shaft.

The grinding and sanding step removes a portion of the thickness of outer layer 25 to leave a desired, preferably substantially smooth, outer diameter with a resulting color pattern. In some embodiments, shown for example in FIG. 7A, the final color pattern may be irregular to form a camouflage pattern. Traditional colors used in camouflage patterns are selected from shades of green, brown, black, white, gray and silver. However, many animals are colorblind, so camouflage patterns may incorporate a variety of colors, other example colors include blue and orange. In alternate embodiments, illustrated with one example in FIG. 7B, the final color pattern may be regular, for example a round or spiral striped pattern or a diamond weave for decoration or shaft identification.

In still further alternate embodiments, shown with arrows 8′ and 8″ in FIGS. 8A and 8B, colored fibers can be filament wound to be added to specific, desired portions along the length of the shaft. This can be done for decorative purposes or to affect certain shaft attributes. For example in FIG. 8A, one or more colored plies 124 and/or 126 can be added to the forward portion of the shaft near arrowhead section 12, to move the balance point of the shaft, increase the shaft weight and to strengthen the arrowhead connection. Alternately in FIG. 8B, one or more colored plies 124 and/or 126 can be added near the rear fletching 14 and nocking section 16 of the shaft for decoration or to move the balance point rearwardly, to add weight and/or to strengthen the nocking point section.

In additional alternate embodiments, arrow shafts made in accordance with the present invention take advantage of properties provided by metal-coated fibers. The metal coatings may be the same color or different colors from the graphite fibers. All or a portion of the fibers in the may be metal coated. Examples of coating metals which may be used on fibers include: nickel, titanium, platinum, zinc, copper, brass, tungsten, cobalt, gold and silver. In addition to different visual effects and colors, various metals, such as copper and nickel, have varying attributes and are used in different proportions to provide different degrees of weight, strength, and vibration absorption. The metal coating may be vapor deposited on the fibers; alternately the metal coating may be electroplated onto the fibers. The metal coating may bond to the fibers or form sheaths around them. By way of illustration, the metallic coating may have a thickness between 400 Angstroms and 2.5 microns depending on the desired weight and appearance.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 

1. A method of making an arrow shaft having multiple graphite plies, comprising: a) forming an arrow shaft core of at least one filament wound or sheet-rolled fiber reinforced graphite plies around a mandrel; b) winding said core with a first filament wound ply including at least a first color; c) winding said core with a second filament wound ply including at least a second color differing from said first color; d) wherein said first filament wound ply and said second filament wound ply form an arrow shaft outer layer with a thickness having an outer diameter equal to or greater than the desired shaft finished outer diameter; e) removing said shaft from the mandrel; and, f) defining an arrowhead mounting portion and a nocking point portion on said shaft.
 2. The method of claim 1, comprising finishing said outer layer to form a substantially smooth finished outer diameter.
 3. The method of claim 2, comprising removing at least a portion of the thickness of said outer layer to leave a shaft with a total diameter equal to the desired shaft finished outer diameter.
 4. The method of claim 2, comprising leaving an irregular color pattern of at least two different colors viewable on the outer surface of said outer layer.
 5. The method of claim 4, wherein said at least two different colors are selected from the group consisting of green, brown, black, white, gray and silver.
 6. The method of claim 2, comprising leaving a regular color pattern of at least two different colors viewable on the outer surface of said outer layer.
 7. The method of claim 1, comprising wrapping said core with a third filament wound ply of at least a third color differing from said first color and said second color.
 8. The method of claim 7, comprising leaving an irregular final color pattern of at least three different colors viewable on the outer surface of said outer layer.
 9. The method of claim 7, comprising leaving a regular final color pattern of at least three different colors viewable on the outer surface of said outer layer.
 10. The method of claim 1, wherein at least one of said first filament wound ply and said second filament wound ply includes metal-coated fibers.
 11. A method of making an arrow shaft having multiple graphite plies, comprising: a) winding filaments including at least a first color around a mandrel; b) winding filaments including at least a second color differing from said first color around the mandrel; c) wherein said filaments are incorporated in the thickness of an arrow shaft, and wherein said first color and said second color create a color pattern wherein said color pattern extends through at least a substantial portion of the thickness of the shaft; d) removing said shaft from the mandrel; and, e) defining an arrowhead mounting portion and a nock mounting portion on said shaft.
 12. The method of claim 11, comprising finishing the outer surface of said shaft and leaving said first and second colors at least partially viewable on said outer surface.
 13. The method of claim 12, comprising leaving an irregular color pattern of at least two different colors at least partially viewable on said outer surface of said shaft.
 14. The method of claim 12, comprising leaving a regular color pattern of at least two different colors at least partially viewable on said outer surface of said shaft.
 15. The method of claim 12, comprising wrapping a third filament wound ply around the mandrel in forming said arrow shaft, wherein said third filament ply includes at least a third color at least partially viewable on said outer surface of said shaft, and wherein said third color differs from said first color and said second color.
 16. A composite arrow shaft formed from multiple fiber reinforced graphite plies, comprising: a) a core for an arrow shaft having two ends, wherein said core is formed of at least one filament wound or sheet-rolled fiber reinforced graphite plies; b) an outer layer of one or more plies filament wound around said core to form an arrow shaft with a desired total diameter, wherein said outer layer includes filaments of at least two different colors; c) an arrowhead mounting section at one end of said shaft; and, d) a nock mounting section at the opposing end of said shaft.
 17. The arrow shaft of claim 16, wherein said outer layer includes filaments of at least three different colors.
 18. The arrow shaft of claim 16, wherein said outer layer displays an irregular color pattern.
 19. The arrow shaft of claim 18, wherein said irregular color pattern is a camouflage pattern.
 20. The arrow shaft of claim 18, wherein said at least two different colors are selected from the group consisting of green, brown, black, white, gray and silver.
 21. The arrow shaft of claim 16, wherein said outer layer displays a regular color pattern.
 22. The arrow shaft of claim 16, wherein said outer layer has a thickness and said at least two different colors are filament wound substantially through at least the entire thickness of said outer layer.
 23. The arrow shaft of claim 22, wherein said core is filament wound and said at least two different colors are filament wound through said core.
 24. The arrow shaft of claim 16, wherein said outer layer includes at least one filament wound layer having metal-coated fibers.
 25. A composite arrow shaft formed from multiple fiber reinforced graphite plies, comprising: a) a first filament wound portion including filaments of a first color; and, b) a second filament wound portion including filaments of a second color; c) wherein said first filament wound portion and said second filament wound portion are included in the length of an arrow shaft; and, d) wherein said first color is different from said second color.
 26. The arrow shaft of claim 25, wherein said first filament wound portion extends along a portion of the length of said shaft for less than the entire shaft length.
 27. The arrow shaft of claim 26, wherein said first filament wound portion is adjacent an arrowhead section of the shaft.
 28. The arrow shaft of claim 26, wherein said first filament wound portion is adjacent a nock mounting section of the shaft.
 29. The arrow shaft of claim 26, wherein said first filament wound portion is along a first portion of the length of the shaft and said second filament wound portion is along a second portion of the length of the shaft. 